BREAKING: implement separate web workers

There are now separate web and queue workers.

The configuration entry `clusterLimit` has been replaced by
`clusterLimits` which allows separate configuration of web and
queue workers.

Changelog: Changed

.config/example.yml

@@ -78,8 +78,11 @@ redis:
 # Whether disable HSTS
 #disableHsts: true
 
-# Number of worker processes
-#clusterLimit: 1
+# Number of worker processes by type.
+# The sum must not exceed the number of available cores.
+#clusterLimits:
+#  web: 1
+#  queue: 1
 
 # Job concurrency per worker
 # deliverJobConcurrency: 128

packages/backend/src/boot/master.ts

@@ -66,7 +66,7 @@ export async function masterMain(): Promise<void> {
 	bootLogger.succ('FoundKey initialized');
 
 	if (!envOption.disableClustering) {
-		await spawnWorkers(config.clusterLimit);
+		await spawnWorkers(config.clusterLimits);
 	}
 
 	bootLogger.succ(`Now listening on port ${config.port} on ${config.url}`, null, true);
@@ -139,16 +139,26 @@ async function connectDb(): Promise<void> {
 	}
 }
 
-async function spawnWorkers(limit = 1): Promise<void> {
-	const workers = Math.min(limit, os.cpus().length);
-	bootLogger.info(`Starting ${workers} worker${workers === 1 ? '' : 's'}...`);
-	await Promise.all([...Array(workers)].map(spawnWorker));
-	bootLogger.succ('All workers started');
+async function spawnWorkers(clusterLimits: Required<Config['clusterLimits']>): Promise<void> {
+	const modes = ['web', 'queue'];
+	const total = modes.reduce((acc, mode) => acc + clusterLimits[mode], 0);
+	if (total > os.cpus().length) {
+		bootLogger.error(`configuration error: cluster limits total (${total}) must not exceed number of cores (${os.cpus().length})`);
+		process.exit(78);
+	}
+
+	const workers = new Array(total);
+	workers.fill('web', 0, clusterLimits.web);
+	workers.fill('queue', clusterLimits.web);
+
+	bootLogger.info(`Starting ${total} workers...`);
+	await Promise.all(workers.map(mode => spawnWorker(mode)));
+	bootLogger.succ(`All workers started`);
 }
 
-function spawnWorker(): Promise<void> {
+function spawnWorker(mode: 'web' | 'queue'): Promise<void> {
 	return new Promise(res => {
-		const worker = cluster.fork();
+		const worker = cluster.fork({ mode });
 		worker.on('message', message => {
 			if (message === 'listenFailed') {
 				bootLogger.error('The server Listen failed due to the previous error.');

packages/backend/src/boot/worker.ts

@@ -1,3 +1,4 @@
+import os from 'node:os';
 import cluster from 'node:cluster';
 import { initDb } from '@/db/postgre.js';
 
@@ -7,12 +8,21 @@ import { initDb } from '@/db/postgre.js';
 export async function workerMain(): Promise<void> {
 	await initDb();
 
+	if (!process.env.mode || process.env.mode === 'web') {
 		// start server
 		await import('../server/index.js').then(x => x.default());
+	}
 
+	if (!process.env.mode || process.env.mode === 'queue') {
 		// start job queue
 		import('../queue/index.js').then(x => x.default());
 
+		if (process.env.mode === 'queue') {
+			// if this is an exclusive queue worker, renice to have higher priority
+			os.setPriority(os.constants.priority.PRIORITY_BELOW_NORMAL);
+		}
+	}
+
 	if (cluster.isWorker) {
 		// Send a 'ready' message to parent process
 		process.send?.('ready');

packages/backend/src/config/load.ts

@@ -54,6 +54,23 @@ export default function load(): Config {
 
 	if (!config.redis.prefix) config.redis.prefix = mixin.host;
 
+	if (!config.clusterLimits) {
+		config.clusterLimits = {
+			web: 1,
+			queue: 1,
+		};
+	} else {
+		config.clusterLimits = {
+			web: 1,
+			queue: 1,
+			...config.clusterLimits,
+		};
+
+		if (config.clusterLimits.web < 1 || config.clusterLimits.queue < 1) {
+			throw new Error('invalid cluster limits');
+		}
+	}
+
 	return Object.assign(config, mixin);
 }
 

packages/backend/src/config/types.ts

@@ -45,7 +45,10 @@ export type Source = {
 
 	accesslog?: string;
 
-	clusterLimit?: number;
+	clusterLimits?: {
+		web?: number;
+		queue?: number;
+	};
 
 	id: string;